From 320f6693097bf89d67f9cabad24a2b911e23073f Mon Sep 17 00:00:00 2001 From: Marcelo Schmitt Date: Fri, 12 Jul 2024 16:21:03 -0300 Subject: [PATCH] spi: bitbang: Implement support for MOSI idle state configuration Some SPI peripherals may require strict MOSI line state when the controller is not clocking out data. Implement support for MOSI idle state configuration (low or high) by setting the data output line level on controller setup and after transfers. Bitbang operations now call controller specific set_mosi_idle() callback to set MOSI to its idle state. The MOSI line is kept at its idle state if no tx buffer is provided. Acked-by: Nuno Sa Reviewed-by: David Lechner Reviewed-by: Jonathan Cameron Signed-off-by: Marcelo Schmitt Link: https://patch.msgid.link/de61a600b56ed9cb714d5ea87afa88948e70041e.1720810545.git.marcelo.schmitt@analog.com Signed-off-by: Mark Brown --- drivers/spi/spi-bitbang.c | 24 ++++++++++++++++++++++++ include/linux/spi/spi_bitbang.h | 1 + 2 files changed, 25 insertions(+) diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c index afb1b1105ec2..ebe18f0b5d23 100644 --- a/drivers/spi/spi-bitbang.c +++ b/drivers/spi/spi-bitbang.c @@ -54,21 +54,28 @@ static unsigned int bitbang_txrx_8(struct spi_device *spi, struct spi_transfer *t, unsigned int flags) { + struct spi_bitbang *bitbang; unsigned int bits = t->bits_per_word; unsigned int count = t->len; const u8 *tx = t->tx_buf; u8 *rx = t->rx_buf; + bitbang = spi_controller_get_devdata(spi->controller); while (likely(count > 0)) { u8 word = 0; if (tx) word = *tx++; + else + word = spi->mode & SPI_MOSI_IDLE_HIGH ? 0xFF : 0; word = txrx_word(spi, ns, word, bits, flags); if (rx) *rx++ = word; count -= 1; } + if (bitbang->set_mosi_idle) + bitbang->set_mosi_idle(spi); + return t->len - count; } @@ -78,21 +85,28 @@ static unsigned int bitbang_txrx_16(struct spi_device *spi, struct spi_transfer *t, unsigned int flags) { + struct spi_bitbang *bitbang; unsigned int bits = t->bits_per_word; unsigned int count = t->len; const u16 *tx = t->tx_buf; u16 *rx = t->rx_buf; + bitbang = spi_controller_get_devdata(spi->controller); while (likely(count > 1)) { u16 word = 0; if (tx) word = *tx++; + else + word = spi->mode & SPI_MOSI_IDLE_HIGH ? 0xFFFF : 0; word = txrx_word(spi, ns, word, bits, flags); if (rx) *rx++ = word; count -= 2; } + if (bitbang->set_mosi_idle) + bitbang->set_mosi_idle(spi); + return t->len - count; } @@ -102,21 +116,28 @@ static unsigned int bitbang_txrx_32(struct spi_device *spi, struct spi_transfer *t, unsigned int flags) { + struct spi_bitbang *bitbang; unsigned int bits = t->bits_per_word; unsigned int count = t->len; const u32 *tx = t->tx_buf; u32 *rx = t->rx_buf; + bitbang = spi_controller_get_devdata(spi->controller); while (likely(count > 3)) { u32 word = 0; if (tx) word = *tx++; + else + word = spi->mode & SPI_MOSI_IDLE_HIGH ? 0xFFFFFFFF : 0; word = txrx_word(spi, ns, word, bits, flags); if (rx) *rx++ = word; count -= 4; } + if (bitbang->set_mosi_idle) + bitbang->set_mosi_idle(spi); + return t->len - count; } @@ -192,6 +213,9 @@ int spi_bitbang_setup(struct spi_device *spi) goto err_free; } + if (bitbang->set_mosi_idle) + bitbang->set_mosi_idle(spi); + dev_dbg(&spi->dev, "%s, %u nsec/bit\n", __func__, 2 * cs->nsecs); return 0; diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h index d4cb83195f7a..c92cd43a47f4 100644 --- a/include/linux/spi/spi_bitbang.h +++ b/include/linux/spi/spi_bitbang.h @@ -24,6 +24,7 @@ struct spi_bitbang { #define BITBANG_CS_ACTIVE 1 /* normally nCS, active low */ #define BITBANG_CS_INACTIVE 0 + void (*set_mosi_idle)(struct spi_device *spi); /* txrx_bufs() may handle dma mapping for transfers that don't * already have one (transfer.{tx,rx}_dma is zero), or use PIO */